Photocomposing machine



Aug.19.195s LROSSETTO mL 2,841,919

PHo'rocoMPosING MACHINE /37 W {fro/wsrf Aug. 19, 1958v Filed March l5, 1953 L. ROSSETTQ I'AL PHOTOCOMPOSING'MACHINE l2 Sheets-Sheet 2 7- W fron/vin Aug. 19, 195s L. Rossum ETA'. 2,847,919

PHOTOCOMPOSING MACHINE Filed March 13, 1953 12 Sheets-Sheet 5 i Y wI Aug- 19, 1958 RossETTo ETAL 2,847,919

PHOTOCOMPQSING Mmmm"` Filed March 13, 1953 12 Sheets-Sheet 4 ,3y WWW/:WOHNEN Aug. 19, 1958 `l.. RossETT'o ETAL 2,847,919 l' PHoTocoMPosING MACHINE Filed March 15, 195s v 12 sheets-sheet 5 /NVE/vro/as L .Qosserro G souAsso/v/ E COLEMAN w. s. Gom/LL ,27 Arron/vers Allg 19, 1958 A l.. Rossiir'ro Erm. 2,847,919

PHOTQCOMPOSING MACHINE Filed larh 15, 1953 l2 Sheets-Sheet 7 /NVE N 70H5 L. ROSSETTO G SQUSSON/ E. COLEMAN Aug 19, v1958 L. Ross'E-r'ro ETAL 2,847,919

PHo'rocoMPosrNG MACHINE 12 sheets-sheet 8 Filed March 13, 1953 INVENTORS L. ROSSETTO G. SOU SSO/V/ E. COLEMAN W 5* GORR/LI.

@WMIMI ATTORNEYS Aug. 19, 1958 LQRossETTo ErAL PHOTOCOMPOSING MACHINE 12 Sheets-Sheef 9 Filed March 13, 1953 /NvE/vrofas L. nossE T70 c; .sol/A sso/v/ E. COLEMAN W.s. Gom/LL 2 7MHWTTORNEYJ -Slmml Aug. 19, 1958 L. RossET-ro ETAL 2,8475919 y Y PHoTocoMPosING MACHINE y Filed Maren 1:5, 1953 y 12 sheets-sheet 1o /NVE/'vrons l.. Rossfrro G. soz/A sso/v/ E. COLEMAN WS. GORR/LI.

Aug. 19, 1958 .1.. RossETTo Eru AL 2,847,919

PHoTocoMPosING MACHINE Filed March 1:5, 195s 12 sheets-sheet '11 f /N VE N TORS l.. ROSSE''TO G. SOUASSON/ E. COLEMAN ,2.7 m5. Goan/LL L. Ross-r'ro ETAL PHo'TocoMPosING MACHINE Aug. 19, 195s f 12 Sheets-Sheet l2 Filed March 15, 1953 .MU -m9 NIFHUMII /Nl/E N 7` ORS L. ROSSE T70 q I Q G. SOUASSON/ E COLEMAN W5 CORR/LL ATTORNE YJ United Statesl Patent Oliice PHoTocoMPosING MACHINE Louis Rossetto, Kings Point, Gino F. Squassoni, Lynbrook, Eugene F. Coleman, Brooklyn, and William Sterling Gorrill, Glen Head, N. Y., assignors to Mergenthaler Linotype Company, a corporation of New York Application March 13, 1953, Serial No. 342,156

48 Claims. (Cl-..954.5)

This invention is directed to an improved photocomposing machine comprising, broadly, a keyboard section, a recording and releasing section, an output section and an optical system for photographing the individual typographical characters `oney after another in the order in which they are to appear in print.

The keyboard section of the improved machine includes an electric typewriter having a main keyboard, an auxiliary keyboard provided with additional character and functional keys, a coding unit-common toy both keyboards, and a series of electrical contacts controlled by said unit for transmitting key selected electrical impulses to the recording and releasingsection. The, coding unit comprises a front and a rear group of toothed spaced-apart code bars arranged directly beneath the typewriter in a suitable supporting frame' and operable selectively by one or another ofa series of overlying fore-and-aft slide bars, the latter being common to the code bars in both groups and controlled from Ithe keyboard through the medium of a constantly ydriven rubber surfaced roller and two series of rotatable` cam elements which are controlled from the various finger keys and arranged respectively along opposite sides of said roller.

The code bars of the front group are devoted to character width and are capable of endwise adjustment collectively to one or another of five different positions in order to select according` to case (for roman, and italics, as well as for small caps, etc.), the proper code assignments for the various characters on both keyboards. Preferably, the code bars of the front group are mounted in a removable tray so that they may be conveniently removed for interchange, whenever a diflerent font or type face is desired. Onr the other hand, the code bars of the rear group are permanently mounted in the keyboard frame and are devotedl to character identification, being adapted when activated to close momentarily the electrical contacts used to impart such information to the recording and releasing section of the machine. In the embodiment illustrated, the individual code bars of both groups are connected to slender rock shafts, from which they are suspended, in order that their functions may more readily be performed through the medium of these shafts. The rear group of code bars includes a so-called universal bar formed without code notches but operable each time a character or space is key-boarded, so vas to close a separate electrical contact for purposes later to be pointed out. It also may be mentioned that the coding unit fui-.ther includes three additional electrical contacts controlled by the adjusting means for the front group of code bars and used in completing character identification code for caps, italics, ligatures, etc.

As aline is being typed or keyboarded and the code developed for the individual `characters and spaces in the manner stated, the electrical impulses for that part of the coded information devoted to character width and word spacing is transmitted first to a decoder (relay bank) and' thence to a line indicator` mechanism associated with the typewriter. These impulses are received 2,847,919 Patented Aug. 19, 1958 by an electromagnetic escapement device which converts them into actuations of selected slides in a squirrel-cage assembly so as to set up cumulative shaft rotations proportional to the desired character widths. Such rotations, through the medium of a lead screw, appear as linear displacements in one direction of a line length pointer along a scale bar and in this way will indicate to operators the total unjustified length of a line during composition. At the same time a separate pointer advances intermittently in the opposite direction along the scale, each time the space bar is depressed, so that the two pointers, when they meety or pass one` another, will indicate the initial and final limitations of the justification range of the machine.

When a satisfactory line has been keyboarded, the operator presses an end-of-line key adapted among other functions, and according to the present improvements, to instigate the operation of means for measuring the line remainder (the amount of line length that must be added thereto for proper justification), and converting this distance electronically as itis measured into a train of electrical impulses for computation purposes. Such means, in the preferred embodiment illustrated, includes an electrically operated transparent plate which is provided with opaque grid-like markings andy is movable over a similarly marked transparent plate in the Zone between a photoelectric cell and a lamp for sensitizing it. The electrical output ofthe cell, after amplification, is transmitted to a pick-olf gate unit and thencer to a justification computer wherein the number of impulses from the cell is divided by the number of word spaces in a composed line that have been accumulated in a stepping switch or totalizer of the computer. The arithmetical quotient is then stored on relays in code form, ready for use each time a word-space is to be set up during `the photographing period.

The information transmitted from the coding unit to the line indicator mechanism, as well as the coded information devoted to character identification, is transmitted at the same time over separate circuits to the recording and releasing section ofthe machine or Iso-called memory unit where itis temporarily stored and recorded in code form on an endless loop of magnetic tape. The recording means employed includes, in part, a bank or row of small electromagnets (writing elements) arranged transversely across the tape and adapted, when selectively energized, to produce saturated magnetic dotlike regions thereon. That is to say, and as already pointed out, when a character or space is keyboarded, electrical impulses are generated by the closing of certain electrical contacts of the coding unit (as determined by the code assignment for that particular character) and these pulses are adapted, in turn, to energize 'corresponding magnets in the recording bank for the purpose stated. As soon as a recording is made, the tape is advanced slightly (1/16), due to the closing of the electrical universal contact, and held readyto receive the coded information on the next character.

After the keyboarding of a line has been completed, and' as the end-of-line key is depressed, the tape is rapidly advanced a definite distance so that the keyboarding of the next line may begin and be recorded at the proper start-line station, the recording of each line on the tape always starting at one of two fixed positions thereon. Meanwhile, the tape again is rapidly advanced to carry the coded information for the line already recorded into a position for release by a second bank or row of small electromagnets reading elements) during intermittent advance of the tape. The reading elements, like the writing elements, are arranged transversely across the tape but -are adapted when energized by the passage of the magnetic dots thereon to generate voltage 3 pulses which, after amplifiction, are used selectively according to the code assignments for the different characters and spaces in the optical system and also in the output section of the machine.

As the tape continues its intermittent advance, during the writing of the second line, the recording thereon for the first line, after being released by the bank of reading elements, is carried through the magnetic held of an erasing head or permanent magnet which obliterates all magnetic dots of such recordings and at the same time keeps the tape itself fully magnetized. lf a recorded line happens to be the last one in the text, the actuation of the end-of-line key through the medium of relays is adapted, after the tape is rapidly advanced, to initiate the intermittent advance movement thereof which continues iuntil all of the coded information thereon has been released in the manner just stated, and the tape again is stopped in the start-of-line position. Separate motordriven mechanical drive trains, later to be described, are used to produce the desired intermittent writing and reading movements of the tape as well as the rapid advance movements thereof through any unused distances at the end of each recorded line. It may be mentioned that there are at least sixteen electromagnets in each of the two banks or rows associated with the magnetic tape of the recording and releasing section, nine being devoted to character identification, five to character width and two for the space bar and end-of-line key, respectively.

Amplified impulses from selected magnets of the reading group for character identification are directed to a decoder where they are set up in a relay tree which permits voltage pulses from a timing generator to be transmitted to the optical system of the machine where they in turn operate a shutter assembly so as to expose the individual characters of a composed line one after another in the order in which they should be photographed. The characters are transparent on an opaque background and arranged in rows and columns on a glass font plate or matrix. Monochromatic light from a mercury arc is directed to the character matrix by a condenser lens assembly and light from the desired character, after passing through a collimator lens and a pair of crossed diffraction gratings, is imaged by a second lens at a common aperture which is located on the optical axis of the optical system and formed in a screen for masking the rest of the images. The character image at the aperture then is reproduced on a photographic film by a final lens capable of adjustment toward and from the film to change the point size of the font in use, as desired.

The film is clamped in a spring propelled carriage arranged in front of the final lens and movable to advance the film intermittently across the optical axis of the system as the individual characters of a line are being successively photographed. Such movements of the film carriage are controlled from an electromagnetic escapement device through the medium of a sine bar and actuating means therefor later to be described. The escapement device is similar to the one mentioned for the line indicator mechanism, comprising magnets arranged about a rotatable squirrel cage drum and sub* ject to being energized according to the angular position they occupy so as to permit corresponding shaft rotations proportional to the character widths and word spaces. In other words, these shaft rotations in turn, and through intermediate connections, determine the extent of the step by step movements of the film carriage while a line is being photographed.

Impulses from the reading electromagnets devoted to character width are directed, after being amplified, to a second decoder where they too set up a relay tree that permits voltage pulses from the timing generator to energize selectively one or another magnet in the escapement device and allow the film carriage to move the proper distance. The character width circuits also include a gate 4 relay electrically connected to the justification storage unit before referred to, so that after the pulses from the reading magnet for the space bar have been amplified, the gate relay will be closed in order to permit information from said storage unit to pass and set up the relay tree of the character width decoder. As a result, voltage pulses from the timing generator are allowed to energize the proper magnet of the escapement device for the film carriage, and thus permit the latter to advance the necessary distance for a word space of a justified line.

After the last character of a line has been photographed the film carriage is automatically restored to its normal position by electro-mechanical means as the endof-line relay and amplifier are energized. As the carriage arrives in its start-of-line position, it is adapted in turn to operate an electric double-contact switch which causes a charged condenser toV instigate the operation of electrically controlled means whereby the film first is unclamped from the carriage, then advanced a step for line spacing, and finally reclarnped to the carriage in proper position for the next exposure.

The keyboard unit also includes two other auxiliary keys, i. e., a quad key and an erase key, the former operable when it is desired to quad out short lines to the proper justifying length as shown on the line indicator, and the latter (erase key) operable to remedy any mistakes that may be made in composition during the keyboarding of a line. When the quad key is actuated and held depressed it is adapted, through the medium of a relay, to energize a non-justifying minimum space relay for setting up an appropriate signal which is transmitted to the character width decoder during a period when the gate relay associated therewith is closed. In addition, the quad relay energizes the end-of-line relay so that the latter may proceed to perform its normal functions as already indicated. Operation of the erase key, which is permitted during the composition of the second line after the first line is read out, is adapted through the medium of relays, including the one for end-of-line, to cause two uninterrupted rapid advance cycles of both driving trains for the tape, and in this way not only carry the second or defective line past the erase magnety but also locate the tape again in its start-of-line position.

The construction of the parts in the various organs of the machine and the manner in which they function will best be understood from the detailed descriptionto follow. However, it may be well to state at this point that the present machine, while capable of operating on any desired unit system, is herein shown and described as operating on an l8-unit basis, that is to say, i8 units to the em, the characters varying in set width on that basis.

ln the accompanying drawings, the improved machine has been shown more or less schematically in preferred form only and obviously many changes and variations may be made therein without departure from the invention involved. It should therefore be understood that the invention is not limited to any specific form or embodiment except insofar as such limitations are specified in the appended claims.

Referring to the drawings:

Figs. l and l-A together show a complete electrical block diagram of the improved photocomposing machine;

Figs. l-B, l-C and l-D show schematically the steps employed in justifying a composed line by adding the spaces obtained electronically to the minimum spaces in the line;

Fig. 2 is a side elevation of the electric typewriter partly in section and broken away to show portions of the coding mechanism;

Fig. 3 is a vertical section through the coding mechanism;

Fig. 4 is a detail rear elevation of a portion of the supporting frame for the code bars, showing the location of the quad and erase switches;

Fig. S is a vdetail showing ya portion of the character width tray and the manner of supporting the Vcode bars therein;

Fig. 6 is a front elevation of the main `and auxiliary members ot the electric typewriter showing the main and auxiliary keyboards and partly broken away to show parts of the coding mechanism;

Fig. 7 is a detail perspective of the space bar switch and its actuating fore-and-aft slide bar;

Fig. 8 is a perspective view showing schematically the keyboard coding mechanism;

Fig. 9 is a detail vertical section showing the key controlled linkage for tripping the individual cam elements which actuate the foreandaft bars of the coding unit;

Fig. 10 is a schematic perspective view of the line indicator and line remainder pick-olf mechanisms, showing also the power drive for the lead screw and the intermediate electro-magnetic escapement for controlling the partial rotations of said screw;

Fig. 11 is atop plan view showing the electronic means employed for measuring the line remainder; Y

Fig. 12 is a detail indicating the passage of light rays through the two grid plates as one is moved relatively to the other during the measuring operation;

Fig. 13 is a fragmentary detail showing a portion of the escapement drum and the associated stop for arresting actuated slides in said drum;

Fig. 14 is a detail face view of the knob for setting the banking nut for the line length pointer slide;

Fig. 15 is a perspective view showing schematically the memory assembly;

Fig. 16 is a perspective view showing schematically the optical system used in the improved machine, and the individual parts thereof appropriately labeled;

Fig. 17 is a perspective view showing schematically part of the shutter assembly of the optical system;

Fig. 18 is a horizontal section through the drums and character matrix of the shutter assembly;

Fig. 19 is a detail end View showing one of the shutter drums in its closed position, and the spring controlled magnetically operated linkage for rotating it through ninety degrees in opposite directions;

Fig. 20 is a detail similar to Fig. 19, showing the shutter drum moved to its open position;

Fig. 21 is a detail showing a portion of the character matrix or fout plate;

Fig. 22 is a perspective view showing schematically the carriage advance and film feed mechanisms;

Fig. 23 is a perspective View showing schematically the mechanism, including an electro-magnetic escapement device, for controlling the advance of the film carriage through the medium of the sine bar, and showing also the mechanism employed for restoring said bar and carriage to their normal position;

Fig. 24 is a detail perspective View showing schematically the means for supporting the sine bar and the spring drum employed to facilitate the operationV of said bar; and

Fig. 25 is a perspective view of the precision stop employed.

Keyboard and coding mechanism the keyboard A1; and a coding unit B located directly beneath the keyboards A1 and A2 in operative relation thereto. The typewriter A (Figs. 2 and 6) also is equipped, as usual, with a paper carriage A3, platen A4, type elements A5, etc., so that the operator may see at elongated constantly driven rubber covered roller AG common vto both keyboards. Vln the embodiment illustrated (Figs. 6, 8 and 9), the cam velements al are mounted at the lower ends and between the side walls of bifurcated spaced-apart supporting members A'7 arranged in two rows (28 in each) disposed along the front and rear sides of the roller A6, those in each row being suspended from a separate pivot rod aa extending cornpletely across the typewriter so as 'to sustain throughsaid members the twelve cam elements required for the auxiliary keyboard A2 as well as the forty-four cam elements required for the main keyboard A1.

The cam elements a7 on one side of the drive roller A6 are staggered in relation to those on the other side and are adapted when rotated by 'said roller, in a manner about to be described, to actuate or push endwise in opposite directions, adjacent fore-and-aft spring controlled slide bars B1 and B2 of a series associated directly with the keyboard coding unit B. As shown best in Fig. 8, the slide bars B1 and B2 are mounted individually in suitable supports B3 and each is provided with a pull spring b for holding them yieldingly in their normal position againstv adjustable stop screws b1 and b2, the former being arranged to engage the rear ends of the bars B1 and the latter arranged to engage the front ends of the bars B2. Operation of the fore-and-aft slide bars B1 is effected, against the tension of their springs b, by rotation of the front row of key controlled cam elements a7 through their engagement with anti-friction rollers b3 carried by said bars; and operation of the slide bars B2 is effected in like manner by rotation of the rear row of key controlled cam elements a7 which are directly opposed to anti-friction rollers b4 carried by the bars B2.

As already stated, the supporting members A7 are each formed with spaced-apart side walls, and the cam elements aI as well as the linkage connecting them to the finger keys of both keyboards A1 and A2, are arranged between said walls. Such linkage (Fig. 9) includes a relatively small bell-crank lever a9 mounted on a pivot pin a10 and operatively connected through the medium of a vertical link a11 and a horizontal lever e112 to the rocking lever a6 of the associated finger key. The shorter arm of the lever a9, as indicated by the dotted lines in Fig. 9, engages the contiguous forked end of the lever :112; and the longer arm thereof, which depends from the pivot pin a1", is offset at its lower end to provide a stop shoulder 113 normally disposed in the path of one or the other of a pair of diametrically opposed studs :114 projecting laterally from one side face of the cam element a7. To maintain the cam element in its inactive position (as determined by the engagement of either of the studs 114` with the stop shoulder 113), the linkage further includes a spring actuated finger 115 which also depends from the pivot pin a1o and terminates in engaging relation to another pair of diametrically opposed studs i116 projecting from the same side face of the cam element a". A Xed horizontal stop rod all, common to all of the members A'7 in each row, serves to locate them in their normal, position (Fig. 9) against the tension of individual pull springs als, with the cam elements a'7 just clearing the outer surface of the constantly driven roller A6. However, when a finger key is actuated, the rocking lever a6 thereof is adapted, through its connection with the bell-crank lever a9, to rock the latter momentarily out of engagement with the active stud 114 of the cam element and permit said cam element to be pressed into frictional engagement with the drive roller A3 by the spring actuated finger 115. As a result, the cam element a7 is turned counter-clockwise (Fig. 9) by the roller A6 to impart, through its engagement with the antifriction roller b4, the required endwise movement to the associated fore-and-aft slide bar B2 of the coding unit B. Of course, in the case of a slide B1, it will be moved forwardly by the engagement of its roller b3 with the roller A6.

The coding assembly (Fig. 8) further includes two sets or groups of elongated spaced-apart code oars Z5 and 3 respectively, and a so-called universal bar 23, all arranged directly beneath the fore-and-aft slide bars B1 and B2 and extending longitudinally of the typewriter substantially throughout its whole length. The rear code bars 2 (six in number) are devoted to character identication and, as shown schematically in Fig. 8, are suspended individually from separate horizontal rock shafts 4 by integral supporting members 5 pinned to said shafts. in their upper edges, the code bars 2 (which are t-shaped in cross section) present rows of tooth-like projections 6 and intermediate clearance notches 7; while the front code bars 3 (5 in number), which are fiat in cross section and devoted to character width, present in their opposite edges short rows of similar tooth-like projections 8 and intermediate clearance notches 9. The code bars 5 also are suspended from separate rock shafts 10 by vertical supporting members 11, but unlike those of the code bars 2, these members 11 engage slots 12 formed longitudinally in the code bars 3 so that the latter may be shifted endwise collectively from and to any one of ive different positions in relation to the overlying foreand-aft slide bars B1, B2 and in this way select, as delsired, the proper character width codes for caps and lower case in either roman or italics, as well as the width codes for small caps, etc. rl`he slide bars B1 and B2 (Fig. 8) also are formed respectively on their lower edges with tooth-like projections b5 which are spaced apart so as to be located normally in operative relation to the projections 6 and 8 of selected code bars 2 and 3. In other words, the arrangement is such that when a character key of either keyboard is depressed, the corresponding slide bar B1 or B2 will be actuated in the manner before described and, through the appropriate code bars 2 and 3, rotate the associated rock shafts 4 and in one direction or the other to develop electrically the proper code assignment or signal for the character desired. To bring about this result, each one of the rock shafts 4 and 10 at the eXtreme right (Fig. 8) is in turn provided with a vertically disposed lever 13 keyed or otherwise secured thereto between its ends and arranged adjacent a normally open contact switch 14. Closing of the switches 14 is effected by one or the other of a pair of studs 15 projecting laterally from the opposite ends of the individual levers 13 and adapted to function irrespective of the direction in which the rock shafts 4 and 10 may be rotated. The code assignment or signal thus developed for any particular character selected then is transmitted in electrical form from the switches 14 to the memory section of the improved machine, before referred to and later to be described.

According to the present improvements, the code bars 3 are arranged in a tray 16 that may readily be removed from the machine for replacement in order to change when desired the character width code for ,text

8 tion, and a separate contact switch 14a controlled by the rocking movement of said shaft is employed for use in connection with the memory unit.

The collective endwise shifting of the five character width code bars 3 to and from their normal or lower case coding position, for the reasons already stated, is effected by the rotation of a pair of spaced-apart edge cams 17 mounted on a fore-and-aft shaft 18 (Fig. 8) and engaging a similarly disposed shift bar 19, which latter is held yieldingly against the cams by pull springs 2' and is operatively connected to the free right hand ends of said code bars. At its front end, the shaft 18 is provided with an appropriate setting dial 21 whereby it may be turned and, through the medium of the cams 17, shift the code bars 3 against the tension of the springs 2@ from their normal position to their several other active positions, as indicated by the numerals l to 5 on the dial. At its rear end, the shaft 18 is extended sufficiently beyond a bearing bracket (not shown) to accommodate three additional cam elements 22 which are disposed in different angular positions thereon and adapted under different settings of the dial 21 to selectively close three electrical contacts 23 associated therewith. That is to say, when caps, ligatures, etc., appearing in the copy are to be composed, the dial 21 is set accordingly in the proper position so that one or two of the contacts 23 may function to complete the character identification code assigned to these characters. The dial 21, of course, is conveniently located on the typewriter A, readily manipulated and the markings thereon easily read by the operator in order to facilitate its setting and resetting, for the purpose just stated.

While the actuation of the space bar a1 or any one of the functional finger keys a2, a4 and a5, is adapted through the release of a cam element a7 to cause the operation of a fore-andaft slide bar of the coding unit, these particular bars B1 and B5 (Figs. 2, 3, 4, 6 and 7) are devoid of the tooth-like projections b5 and each is arranged to operate directly an electrical contact switch associated therewith. For example, when the space bar al is actuated, one of the two slide bars B4, to which it is connected (Figs. 3 and 6), will be moved forwardly away from its stop screw b1 against the tension of its spring b so as to close an electrical switch A8 attached to the front face of the supporting frame for the typewriter A; and when the end-of-line key a2 is actuated, the other slide bar B4 will be moved forwardly in like manner to close a second contact switch A9 also attached to the front face of said supporting frame.

Unlike the slide bars B4, the two fore-and-aft slide bars B5 are capable of endwise movement rearwardly in opposition to their springs b and away from their stop screws b2 in order to close one or the other of two electrical switches A1o and A11 which are secured to the rear face of the typewriter supporting frame. Consequently, when the quad key a4 is de aressed, it is adapted to cause the rearward movement of the slide bar B5 associated therewith as `well as the resultant closing of the switch A10; and when the erase key a5 is actuated it is adapted to function in a similar fashion through the other slide bar B5 to close the electrical switch A11. In this way, the space bar a1 and the finger keys a2, a4 and a5 are enabled when actuated to energize separate relays which in turn permit them through other electrical equipment to perform their individual functions in a manner later to be pointed out.

Line indicator and line remainder pick-ofit mechanism As a line is being composed on the typewriter, information from the five code bars 3 devoted to character width, as well as that from the space bar a1, is transmitted electrically through relays of a decoder 24 (Fig. 1) to an electro-magnetic escapement device C (Fig. l0) which forms part of a line indicator mechanism associated with the typewriter. The space bar a1 of the keyboard A1 as well as the end-of-line key a2 also are electrically connected through separate relays to other parts of the mechanism about to be described.

l As best shown schematically in Fig. l0, the escapement device C comprises a drum C1 keyed or otherwise secured to a horizontal drive shaft C2 and slotted longitudinally so as to accommodate a series of twenty-live equally spaced-apart slides C movable endwise individually to and from active position. Actuation ofthe slides C is elected by the selective energization of one or another of a series of twenty-four stationary electro-magnets C3 disposed concentrically about the axis of the drum with their pivoted arms C1 arranged in engaging relation to the protruding ends of a corresponding number of the slides C. While only eighteen such electromagnets would be needed for most characters, which have a set width of less than one em, there are some characters which have a greater width and which run as high as 24 units, such as the.ligatures"l and The arms C1 of these indexing magnets C3 are controlled by pull springs C2 which hold them yieldingly against stop pins C3 properly spaced from the magnet cores. When one of the magnets C3 is charged and the associated slide C is actuated by the magnet arm C1, the opposite end of the slide will be projected suliciently far beyond the end of the drum C1 to engage a fixed stop element C1 and thus positively arrest the drum during its rotation by the drive shaft C2. At such time, the projecting end of the active slide C will be located directly in front of the arm C of a single release magnet C4 adapted to function substantially in synchronism with the charging of the magnet C3 next selected, so as to push the arresting slide Cout of engagement with the stop element C4 and back to its original or normal position. The arm C5 of the release magnet C4, like the arms of the magnets C3, is controlled by a pull spring C6 and held yieldingly thereby against a stop pin C7 in proper spaced relation to the core of said magnet, In this way, the information sent out by the keyboard coding unit B for the different character widths, and that sent out by the space bar a1 (representing 3 units as the minimum word space), is converted into partial shaft rotations which are used to operate the line indicator mechanism.

The drive shaft C2 (Fig. 10) receives its motion from an electric motor C5 through the medium of a slip clutch C9, and at its free end said shaft is provided with a spur gear for imparting its partial rotations to a lead screw C7, the shaft C3 of the latter being extended beyond one of its bearing posts 26 and having secured thereto an arm C9 and also a gear C19, which latter meshes constantly with the spur gear 25 and is thicker than usual for reasons presently to appear. The indicator mechanism also includes a scale bar C3 having graduated em and en markings reading preferably from right to left; and also a line-length pointer C11 movable along the scale bar by the partial rotations of the lead screw C7 so asv to indicate the length of a line as it is being composed. The pointer C11 is attached to a supporting block C9 arranged astride the lead screw C7 so that it may be raised and lowered to break and make threaded engagement therewith. For this purpose, the block C9 (Fig. 10) is slidably connected to the cross rod 27 of a bail member 2S, the side arms 29 of which-are secured to a horizontal rock shaft 30 mounted in suitable bearings of the supporting frame. Raising of the pointer block C9 takes place in opposition to a pair of pull springs 31 connected to the side arms of the bail member 28 and acting to hold the latter in its normal position upon vertically adjustable screw elements 32 with the threads of the pointer block C9 in proper orientation with those of the lead screw C7.

To locate the line-length pointer C11 in any pre-selected start-of-line position, the assembly further includes a bankand is provided at one end with a knob or handle C13 whereby it may be rotated in one direction or the other to set the banking nut in different positions. The banking nut C19 is constrained to ride upon a horizontal guide rail 33, as it is being set for lines of a diiferent justied length, and carries an electrical contact switch 34 controlled by an offset projection C14 of the pointer block C9 as the latter is moved to and from its starting position against the nut C19.

Such settings of the banking .nut C19 are also indicated on the scale bar C8 by a second pointer C15 which is attached to the nut and projects slightly above, the rear side face of the scale bar. To obtain the accuracy required in setting the banking nut C10 in its different positions (i. e. within the unit fractions of one ern), the turning knob C13 for the screw rod C12 is formed in its outer side face with 18 marked peripheral notches C13 (Figs. 10 and 14), and a spring-pressed pawl or detent C17 is employed to yieldingly hold the knob andscrew rod, through its `engagement with one or another of said notches, in different angular positions. However, before setting the banking nut C19, the supporting block C9 for the line-length pointer must be lifted manually out of engagement with the lead-screw C7, which then is at rest and capable of a slight endwise adjustment, against the tension of a compression spring C13, by a shallowstepped cam surface C19 formed on the inner surface l of the knob C13 and engaging an antifriction roller (not shown) on the contiguous end of the screw shaft C9.

A spring drum C11, connected to the pointer block C9 by a exible band or cable C29, tends constantly to urge the block toward its start-line position as a line is being composed and normally holds it yieldingly against the banking nut C19. After the banking nut C19 has been properly reset, the pointed block C9 is allowed to move under manual control back along the cross rod 27 of its supporting bail member 28 until it is arrested by the nut C19 and then is lowered into proper engagement with the lead screw C7, the preceding endwise adjustment of said screw by the stepped cam surface C19 of the knob C13 serving to insure and facilitate such engagement.

The line indicator mechanism also includes a space pointer C21 located near the right hand end of the scale bar C8 and movable each time the space bar a1 is actuated,

in increments of 21/ 18 ems, toward the line-length pointer C11. As shown best in Fig. 10, the space pointer C21 is secured to an angular slide member C12 mounted on the scale bar C3, and its intermittent movements are effected against the tension of a pull spring C22 by a rotary solenoid C13 through the medium of two pawls C23 and C24, respectively, which engage a ratchet bar C25 of said slide member. The advancing pawl C23 is pivotally connected to the free end of the spring controlled arm C29 of the solenoid C13 and isk formed with a nose portion C27 overlying a similar projection C28 on the retaining pawl C24, so that both pawls may be disengaged from the ratchet bar C25 simultaneously preparatory to a resetting of the slide member by its control spring C22. Therefore, the retaining pawl C21 is mounted to swing about a fixed pivot and connected by a vertical link C29 to the arm C39 of another rotary solenoid C14. A light pull spring C31, attached to the solenoid arm C39, holds the retaining pawl C2I1 yieldingly engaged with the ratchet bar C25. As thus arranged, every time the space bar a1 is depressed during composition, the solenoid C13 Will be energized momentarily and move the space pointer C21 step by step along scale bar C8 in the direction of the approaching line-length pointer C11, while the retaining pawl C24 acts to sustain the space pointer against the tension of the spring C22 in its different advanced positions.

After a line is completely composed .to the proper justifying length and the line pointer C11 has registered with or passed the space pointer C21, the remaining distance between the line-length pointer and a zero mark on the scale bar C8 is measured electronically by meansy yet to be described, and the solenoid C1'1 then is energized to lift the pawls C23 and C24 out of engagement with the ratchet bar c so that the space pointer C21 may be returned to its starting position by the pull spring C22. At or about the same time, several other operations incidental to the line indicator mechanism are effected electrically or electro-mechanically in a predetermined order of succession. That is to say, a single pulse from an electrical source 35 (labeled Time Delay on the block diagram in Fig. l) is transmitted to the release magnet C4 of the escapement device C before described, in order to permit the drum C1, as well as the drive shaft C2, to turn idly through a sufiicient number `of degrees to swing the arm C9 of the lead screw shaft extension e9 into engagement with an angular stop element 36 (Fig. l0) and thus positively arrest the rotation of the lead screw CI in its proper start-line position.

Meanwhile, however, the supporting block C9 for the Vline-length pointer C11 first is raised automatically, in I opposition to the pull springs of the bail member 28, out 7' of its engagement with the threads of the lead screw C, and thereupon is pulled back along the cross rod 27 of the bail member until stopped by the banking nut C11l preparatory to being lowered into engagement again with the threads of the lead screw. Raising and lowering of the pointer block C9 is accomplished at such times by first energizing and then dei-energizing a third rotary solenoid C15 (Fig. l0) having an arm C32 arranged in engaging relation to a crank arm 37 which projects rearwardly from the rock shaft 30 of the bail member 28. Energizing of the solenoid C15 to raise the pointer block C9 is effected by the closing of one contact of a two-way switfah 3S; and the de-energizing of said solenoid to permit the springs 31 of the bail member to act in lowering the pointer block is effected as the latter banks against the nut C19 and the contact switch 34 on the nut is opened by the offset projection C14 of the pointer block. At this point it may be stated that the actuation of the two electrical switches 38 and 34, respectively, in the manner and for the purpose just stated, also controls the energization v and de-energization of the solenoid C13 for resetting the space pointer C21.

The angular stop element 36 (Fig. l0), for arresting the rotation of the lead screw C7, is pivotally mounted between its ends and held normally by a pull spring 39 ing of the latter is effected also by the closing ofthe same contact of the two-way switch 38 but is adapted to take place slightly before the solenoid C15 is energized, so that the rotation of the lead screw C'1 will be stopped in its proper angular or start-line position before the pointer block C9 is disengaged therefrom.

According to the present improvements, the means employed for measuring electronically the line remainder after a line is composed to the proper justifying length (Figs. 10, ll and l2) includes a reciprocable transparent grid plate D slidably mounted for horizontal movement in suitable guideways 4t) and arranged directly in front of a similar stationary grid plate D1 so as to move across the same during its reciprocal movements. The two plates D and D1 are formed with vertical opaque markings d and d1, respectively, spaced apart on an 18-unit basis, said plates being disposed in a space provided between a photo-electric cell D2, located in front of the reciprocable plate D, and an incandescent lamp D3 located behind the plate D1. Normally, the grid plate D is held yieldingly against a stop pin 41 under the inuence of a i pull spring d2 with the opaque markings d thereon coverl ing the transparent spaces between the opaque marking d1 on the stationary grid plate D1 so as to prevent the escape of the light rays from the lamp D3 through the plate D.

The line remainder of course will vary according to the length of the lines composed or, as previously stated, when the line-length pointer C11 registers with or passes the space pointer C21. The line pointer C11 then will be located in the justifying zone 0r that between the advanced space pointer C21 and a zero mark (not shown) on the scale bar C3. This mark, however, is exemplified or designated by a stationary gate contact plate 42, and when the reciprocable grid plate D occupies its inactive position shown in Fig. l0, an electrical switch D4 carried thereby will be located in engaging relation to said contact plate. A second gate contact for the switch D1 is provided by the offset flange or projection C14 of the supporting block C9 for the line-length pointer C11 as it stops in the justifying zone. Operation of the reciprocable grid plate D is controlled by a rotary solenoid D5 having an upright arm d3 provided with an antifriction roller d4 arranged to engage a depending projection d5 of the grid plate.

After a line is completely composed and the end-of-line key is actuated, the solenoid D5 is energized by a so-called auxiliary end-of-line relay 43 (indicated on the block diagram in Fig. 1) to impart the active stroke to the reciprocable grid plate D; and, as the latter starts to move, the switch D4 at the leading end thereof will be closed momentarily by the first gate contact 42 in order, first, to sensitize the photo-electric cell D2 and, then, to permit a multiplicity of light `rays from the lamp D3 to be directed thereto through the medium `of the grid plates D and D1 until the switch again is closed momentarily by its engagement with the second gate contact C14. As a result of this operation, the light rays from the lamp D3 are converted by the photo-cell D2 into a corresponding number of electrical impulses (one for each unit measured), which are transmitted through a line remainder pick-off gate 44 (Fig. 1) to a computer and finally used in the justification of the composed line. As the switch engages the second gate contact C14, the photo-cell D2 is tie-sensitized so that a true measure of the line remainder,. as determined by the number of electrical impulses generated in the cell, is obtained. A yielding stop element 46 limits the active stroke of the grid plate D and, as the plate approaches said stop, it is adapted to close a contact of the two-way master switch SS (before mentioned) which thereupon de-energizes the actuating solenoid D5 for said plate and allows the latter to resume its normal position against the stop pin 41.

The justification computer includes a stepping switch or space totalizer 47 (Fig. l), whereby the number of spaces between the words in a composed line are totalized, and a divider 48, wherein the number of electrical impulses from the photo-cell D2 are divided by the number of word spaces, the quotient then being transmitted from the divider first to a justification storage unit 49 and thereafter through a character width gate 50 to a decoder 51 where it is stored on a relay tree in code form ready for use each time a word space is to be set up during the photographing period. If it should happen that one or more pulses remain as a fractional part of the quotient, they will be added successively to those already in the spaces until they are exhausted. For example, if there should be, say, five left-over impulses, as a result of such computation, and which in the present instance represent respectively one-eighteenth part of an em, they will be distributed equally among the first five word spaces in the composed line before it is photographed. See the schematic illustration in Figs. l-B, l-C and l-D. The justification computer is of the well known binary type used in high Speed electronically operated calculators and therefore requires no further explanation.

Recording and releasing mechanism Reference is now directed to Fig. l5, which shows schematically the memory unit and parts of the driving mechanism therefor. This unit temporarily stores character identification, character width, and control informaltlon 1n code form, on an endless magnetic tape E, such information being written across the width of the tape while the latter is at rest by a row of sixteen electromagnets E1 (writing heads) which are energized select1vely according to any given character or space and intended, as previously stated, to magnetize small dotlike regions (not shown) on the outer surface of the tape. The' lirst nine magnets E1 (Fig. l) are devoted to character identification, the next five to character width, and the last two to the space bar a1 by way of a relay 52 and to the end-of-line key a2 by way of a relay 53, respectively.

The magnetic tape E inherently is self-sustaining and along its opposite edges it is perforated so as to engage a pair of spaced-apart sprocket rollers E2 and E3 which are rotatable independently by separate electro-mechanical drive trains, each adapted during successive cycles to cause an intermittent as Well as a rapid advance movement of the tape. That is to say, as the characters and spaces -of a line being composed on the typewriter A are recorded on the magnetic tape Ethrough the selective charging of the electro-magnets E1, the tape is advanced intermittently 1/16 by the sprocket roller E2 until the line is completely composed. Then, as the end-of-line key A2 is actuated, a rapid advance of the tape E by the roller E2 is initiated by the charging of a relay 54 by the relay 53 (Fig. l), in order to locate a following blank section of the tape in the proper start-line position adjacent the row of writing magnets E1 where it is ready to receive the recordings for a second line as it is being keyboarded.

immediately thereafter that section of the tape E bearing first written line, and which for the moment is in loop or festoon form, is rapidly advanced by the sprocket roller E3 a definite distance to carry said line to the reading station where it is located adjacent another row of sixteen magnetic structures E4 (reading elements) preparatory to a second intermittent advance of the tape by said sprocket roller. The rapid advance of the tape E at this time is initiated when a relay 55 (Fig. l) is energized by the end-of-line relay 53; and the following intermittent advance of the tape is initiated and carried on by pulses from a timing generator 56, which makes one complete rotation for each character producing cycle. These pulses are released consecutively by a gate relay 57 associated with the generator and controlled from the relay 55 through an intermediate switch (not shown) and a read initiate relay 5S. Subsidiary rollers E5, associated with the sprocket rollers E2 and E3, hold the tape E constantly engaged therewith and are so arranged as to maintain two opposed loops or bulges therein that may take up a sutiicient length of the tape to permit it to be rapidly or slowly advanced by either sprocket roller to the exclusion of the other. During the second intermittent advance of the tape E and as the magnetized recordings thereon pass the row of reading elements E4, voltage pulses are induced in these elements, which after amplification are used in the output section of the improved machine, later to be described. A strong permanent magnet E,6 (Fig. l5), located directly above the sprocekt roller E3 and slightly beyond the row of reading elements E4, is employed to erase or remove all traces of the dot-like recordings on the tape E as the second intermittent advance thereof is completed.

The drive assemblies for the two sprocket rollers E2 and E3 are identical in form and mode of operation. Therefore, only the assembly for driving the sprocket roller E3 located at the reading station has been shown completely, although schematically, in Fig. l5, and a description of this assembly as well as the reference characters may applyto corresponding parts of the assembly for driving the sprocket roller E2 insofar as the illustration permits. Thus, the shafts E7 and Ea for the rollers E2 and E3, respectively, are rotated in a clockwise direction by separate drive shafts 59 aligned therewith and connected to one end thereof by positive couplings 60. At their other ends, the shafts E7 and E8 are extended beyond the rollers yE2 and E3 and carry pinions E9 for imparting through gears 61, meshing therewith, rotary movements to stub shafts 62 which are provided with edge cams 63 arranged in operative relation to double Contact control switches E10.

A Geneva Wheel E11, formed with eight peripheral slots e, is included in the drive assembly for each of the two sprocket rollers E2 and E3, one of the Geneva Wheels (the one not shown) being operable to cause the intermittent advance of the tape E past the row of writing elements E1, and the other Geneva wheel E11 being operable to cause the intermittent advance of the tape past the row of reading elements`E4. The step-by-step movement of the Geneva wheel E11 is elfected by successive complete revolutions of a spur gear 64 mounted on a lay shaft 65 and driven from a main drive shaft 66 by a smaller gear 67 through the medium of a slip clutch 68. As shown in `Fig. 15, the gear 64 is provided with a stud 69 projecting laterally from one side face thereof and adapted, during each revolution of said gear, to engage `one of the radi'al slots e in the Geneva wheel E11 and apart a 45 turn thereto. completes a revolution, it is stopped by an arm E12 rising from Vfa Apivot rod e1 and formed at its upper end with -a lip e2 normally disposed in the path of a second stud 70 projecting laterally from the opposite side face of the gear .64. A pull spring ea holds the arm E12 yieldingly in such position and a trip magnet E13 is employed `to retract it. Energization of the magnet E13 is Aeffected intermittently by :electrical impulses emanating from the gate relay 57, before mentioned, which is associated with the timing generator 56; whereas, energization of the corresponding magnet (not shown) associated with the drive assembly for thesprocket roller E2 is effected by ythe intermittent closing of the electrical contact 14EL by the universal bar 2a, heretofore described, as a line is being composed on the typewriter. The step-by-step rotation of the Geneva Wheel `E11 is transmitted to the drive shaft 59 for the sprocket roller E3 by means of a gear set 71 and a one-way 4tooth clutch E14, which latter is spring loaded for normal engagement and capable of turning said shaft in one ,direction only.

The Vdriving assemblies for the two sprocket rollers E2 and E3 further include, respectively, a magnetic clutch E15 and a stop device E16. The magnetic clutches are mounted on the drive shafts 59 for the sprocket rollers and are adapted when energized to rotate said shafts at the proper speed to effect the rapid advance of the'tape E toward the writing and the reading stations;,while the stop devices serve positively to arrest such rotation of the drive shafts and in this way locate the tape lengthwise in the proper start writing and start reading positions. The two magnetic clutches E15 each comprise generally a coil assembly drum e4 idling on the associated drive shaft 59, a pair of contact slip rings e5 for an electrical connection to said drum, a spur gear es for rotating the drum and itself driven from the main' drive shaft 66 through a gear train 72, a driving member e'1 attached to the gear e6, and a disk-like member e8 pinned to the drive shaft 59 and adapted when the coil assembly is energized to establish a driving connection between the clutch E15 and the drive shaft 59. At such times, it may be mentioned that the spring loaded driving member of the one-way tooth clutch E1'1 will be cammed out of its engagement with the driven member thereof and permit the latter to slip past it as the shaft 59 starts its rotation by the clutch E15 in initiating a rapid advance movement of the tape E for the reasons already stated. The two magnetic clutches E15 for the respective sprocket rollers E2 and E3 are energized almost simultaneously when the end-of-line key a2 is actuated and the associated relay 53 (Fig. l) is charged. At such times,

As the spur gear 64,

the relay 53 is adapted, first, to close the write rapidadvance-initiating relay 54 and, a few seconds later, to energize the read rapid-advance-initiating relay 55.

Each of the two stop devices E16 for arresting the rotation of the `drive shafts 59 includes merely an electromagnet e9 and an arm elo movable thereby into engaging relation to a stop element e11 which is keyed or otherwise secured to the drive shaft and formed with a straight radially disposed banking surface e12. As best shown in u Fig. 15, the arms elo are arranged in a plane substantially at right angles to that of the shafts S9 and are hingedly mounted at one end on individual pivot rods el?) spaced from said shafts. Normally the arms e are held yieldingly by pull springs e14 in their inactive position out of the path of the stop elements en; however, when the magnets e9 are charged, the arms e10 will be swung upwardly thereby against the tension of their springs and into the path of the stop elements ell so as to positively stop the rotation of the shafts 59 and thus locate the tape E properly in the start reading and start writing position.

If a mistake should happen to `be made in composition as a line is being keyboarded, the corresponding recording on the tape E may readily be erased by striking the erase finger key a5 which thereupon causes an erase relay 73 (Fig. l) to be energized. As a result of such energization, the read initiate relay 58 will be de-energized temporarily but the end-of-line relay 53 will -be charged and allowed to perform all the rest of its functions. In addition, the erase relay 73 energizes the auxiliary endof-line relay 43 as well as a relay 74 in the erase delay circuit so as to prevent the functioning of the magnets e9 for two complete cycles of the tape E and at the same time prevent the deenergization of the magnetic clutches E for driving the sprocket rollers E2 and E3. The relay 74 then de-energizes itself.

When composing lines shorter than the selected length, such as those occurring at the end of paragraphs, etc., the quad key a4 is utilized and when actuated is adapted to energize a quad relay 75 (Fig. 1) which, in turn, energizes a non-justifying, minimum space units relay 76. As a result, the relay 76 sets up the appropriate minimum space signal so that, when the character width gate relay Si) is closed, the signal will be sent to the character width decoder 51. The closing of the gate relay 50 prevents the passage of information from the justification storage 49 to the decoder 5l and is accomplished by grounding certain contacts in said relay. The quad relay 75 also energizes the end-of-line relay 53 so that the latter may perform its normal functions; and when a signal from the end-of-line recording on the tape E is received by an amplier relay 77, the latter sends out an electrical impulse to reset the minimum space relay 76 through the medium ofthe character width gate 50.

To complete the memory unit, a set of conventional amplifiers (represented by the three triangular blocks 78a, 75h and 78c in Figs. l and l-A), associated with the reading elements E1 of said unit, is adapted to convert the small induced voltages therein into substantial electrical impulses for operating the various relays in the output section of the improved machine. Thus, the electrical impulses developed in this way for the identification of any selected character (block 78a) are transmitted to a decoder 79 where they are further amplified by pulses from certain commutator segments of the timing generator S6 and set up four relays of a tree in order to bring about the exposure of the desired character by operating a shutter assembly F which is located, as shown in Fig. 16, in the optical system of the improved machine. At the same time, the small voltages induced by the group of reading elements E4 devoted to character width (block 78h), after being amplified, are converted into electrical impulses and transmitted to the decoder 51 before mentioned. Here, tbese'impulses, likeI those for 16 character identification, are further amplified from certain preselected commutator segments of the timing generator 56 so as to set up relays of a tree in the decoder, which are adapted to control the operation of a film carriage escapement device later to be described and which is indicated by a block labeled P in Fig..1-A.

Electrical impulses are developed and amplified in like manner (triangular block 78C) from the small voltages induced by the single reading element E4 devoted to the space bar a1. These impulses also are transmitted to the decoder 5l where they too set up relays of a separate tree adapted to control, according to word spacing, the operation of the film carriage escapement device which is similar in all respects to the one (C) associated with the line indicator mechanism already described.

Amplified electrical impulses developed from the small voltages of the last reading element, and which are devoted to the end-of-line key a2, are transmitted, after further amplication by pulses from the timing generator 56, to the decoder 51 and thence to the film carriage escapement device above referred to. In this connection, it may be mentioned that when the read initiate relay 58 (Fig. l) is energized as a result of striking the end-of-line key a2, it in turn energizes the gate relay 57 associated with the timing generator 56 and at such times the gate relay is adapted to remove the power from the end-of-line key as well as from the erase and quad keys during the reading cycle.

Optical system The shutter assembly F (Figs. 17 and 18) consists mainly of a set of sixteen rotatable vertically disposed drum-like shutters F1 and a corresponding set of similar horizontally disposed shutters F2 arranged in operative relation to the shutters F1 but spaced sufficiently therefrom to permit the insertion of a font plate G between the two sets, -said plate being provided (as indicated in Fig. 21) with an array of transparent characters g disposed in horizontal and vertical rows on an opaque background. At their opposite ends, the shutters in both sets are mounted in suitable bearing plates F3 and F4 of the assembly frame and are formed with longitudinal slots f1 extending substantially throughout their length, so as to provide appropriate openings for exposures as well as intervening masking sections f2 when the individual shutters are turned through 90 in opposite directions. T o prevent the escape of light (provided by a mercury arc lamp 80) past the shutter assembly F during non-exposing periods, said assembly also includes fixed masking rods f3 interspaced between the shutters F1 and F2. When any selected pair of shutters (i. e. one in each set) are turned to open position to expose a pre-selected character on the font plate G, light from the mercury lamp 80 will be confined to the space occupied by that character.

Turning of the two selected shutters F1 and F2, in the manner and for the purpose just stated, is accomplished i by the energization simultaneously of separate electromagnets f4 (Fig. 17) associated with the shutters, such energization, in the present instance, being effected by two electrical impulses which are directed to each of said magnets in rapid succession from the tree of the decoder 79. As best shown in Figs. 19 and 20, suitable linkage is employed for connecting the individual shutters F1 and F2 to the arms of their respective magnets f4, said linkage including a reciprocable plunger f5 slidably mounted in tubular projections f5 of the framework and operable against the tension of a compression spring f7 by the pivoted arm f8 of the associated magnet f4. The plunger f5 (Fig. 17) is disposed in a plane at right angles to the font plate G1 and preferably in line with the axis of the adjoining shutter so that it may actuate the latter through the medium of a connecting link f9 which is attached off-center to one end thereof.

The arrangement is -such that when a magnet f4 is 

